Lubricant composition



Patented .iuiy 6, 1943 UN i an STATES Parent Wm LUBRICANT ooMrosrrroNRolston L. Bond, Cranford, N. 3., assignor to Tide -Water Associated OilCompany, Bayonne, N. --a corporation of Delaware No Drawing. ApplicationSeptember 27, 1940,

Serial No. 358,662

invention relates to lubricationi concerned with enhancing theutilityand prolonging the useful life of lubricants, especiallypetroleumlubricating oils. Improved lubricating oils for internal combustionengine or other severe lubricant service constitute an importantobjective. Straight petroleum oils of suitable 'viscoslty fail toprovide satisfactory lubrication in many services. Modern internalcombustion engine operation frequently requires lubrication under severeconditions which tend to cause early de'-' terioration of ordinarylubricants resulting in ineifective lubrication and often in enginebreak-' encountered, for example, in automotive engines designed forhigh speed operation entailing high temperatures and high bearingpressures necessitating the use of special bearing surfaces such asthose formed of cadmium-silver and like alloys. Coincidently, serioustrouble results from susceptibility of such special alloy bearings tocorrosion caused by the oil used to provide lubrication therefor.Further dimculties in many modern lubrication services arise from theknown low film strength, or inability to provide efiective lubricationunder severe conditions where high pressures between contacting movingsurfaces are developed, of straight petroleum lubricants.

Accordingly, the present invention is directed generally at bettermentof lubricants derived from petroleum whereby improved operatingcharacteristics in one or more respects may be obtained. In one specificembodiment, the invention is particularly concerned with enhancing andprolonging the utility of lubricants (such as lubricating oils operatingin internal combustion engines) which by reason of origin or degree ofrefining are desirable for effective lubrication under many conditionsbut exhibit pronounced tendencies toward deterioration.

To these and other ends, there is disclosed herein a class of organiccompounds providing new additives useful for incorporation in petroleumlubricating oils, The lubricant of the invention comprises a viscouspetroleum base stock, normally of high quality by conventionallubrication standards, -containing an improvement amount of an organicsulflte additive or inhibitor compound selected from the particularclass described below. a

This class may be generally defined as alkyl or alkyl amine esters ofsulfurous acid conformingto the general formula s=o RX wherein Rdesignates an alkyl or substituted alkyl group; and X may be 0 or N(R).A convenient method for preparing such compounds {is to react, insuitable mola'l proportions, thionyl 1 5: chloride (SOClz) withaliphatic alcohol or secondary aliphatic amine.

In more specific grouping, compounds covered by the aforesaid generalformula may be desig-, nated by the following sub-generic formulae r)R'O wherein the several R's represent the same or different aliphatic orsubstituted aliphatic residues, for example methyl, ethyl, propyl,butyl, amyl, etc., radicals.

Compounds in sub-group (1) may be formed by reacting two mols of analkyl alcohol with one mol of thionyl chloride.

To form compounds in sub-group (2), it is convenient first to react onemol of an alkyl alcohol with one mol of thionyl chloride, andsubsequently treat the reaction product with one mol of a secondaryaliphatic amine.

For the preparation of sub-group (3) compounds, two mols of a secondaryaliphatic. amine are reacted with one mol of thionyl chloride.

The method of preparing lubricant additives comprising compounds of theclass disclosed herein forms no part of the present invention, thesynthesis thereof having been adequately described in availabletechnical literature and texts to reference may be had for instructionin the preparation of particular suitable members of the class.

It will be appreciated that organic sulfites of the type defined hereinwhich are useful as lubricant additives for inhibitor or other serviceare those which are sufllciently oil soluble, substantially waterinsoluble and nonvolatile at service temperatures. These properties willgovern the selection of desired active compounds.

One useful method of evaluating lubricating oils is that utilizing thefamiliar Underwood oxidation testing apparatus. This provides a measureof comparative oil deterioration as evidenced by sludge formation,acidity development and viscosity increase; and coincidently indicatesthe tendency of an oil to corrode sensitive bearing metal alloys. {isconducted for the results reported below, a single cadmium-silverhalf-bearing supported on a 2" x copper baille is mounted in the testchamber and lubricating oil maintained at 325 F. is sprayed continuouslyon the bearing and baiile for a period of hours. A 1500 c. c. sample ofoil is used and is recirculated through the apparatus during the testperiod. The test 011 was a high quality Pennsylvania motor oil of S. A.E. 10 grade to which had been added 0.005% F8203 as iron naphthenate (anoil deterioration positive catalyst) to increase the severity of thetest.

Using this test method the following results were obtained with andwithout an additive compound according to the invention. These resultsclearly demonstrate the effectiveness of an organic sulfite of thegeneral class disclosed as an improvement agent for petroleumlubricants.

In the foregoing table, bearing loss is expressed as grams and is ameasure of corrosion by the test oil. Naphtha' insoluble material isexpressed as per cent of the used oil, neutralization number asmilligrams KOH per gram sample of used oil, carbon residue as per centof the used oil and viscosity increase as per cent of new oil viscosityat 210 F.; all of these characteristics being a measure of oildeteriortaion tendency.

It will be apparent from the foregoing test results that proportions aslow as 0.5% of a composition according to the invention are markedlyefiective in improving the quality and enhancing resistance todeterioration of lubricating oils.

The proportion used in the illustrative example is not of courselimitative; nor will the same selected proportion of additive be used inevery instance. Both the specific sulflte ester used according to theinvention and the lubricating oil environment in which it serves willinfluence the amount of improvement agent added to the oil. Naturally.solubility will vary both as between different sulfite esters of theclass described and as between diflerent lubricating oil stocks to whichthe inhibitors are added. Solubilizing agents may be used but are notcontemplated as especially necessary.

Usually improvement in lubricating oils, particularly for resistance tooxidation or like motor oil service degradation, is obtained withproportions of additive of the order of 0.1% to 1.0% by weight based onthe oil. This is well within the limit of solubility of compounds in thedesignated class. For some services larger proportions, for example 5%to 10% by weight of additive based on the oil, will be useful. As ageneral proposition the invention contemplates and encompasses inintended scope the use of the new additives in all lubricant improvingproportions.

I claim:

1. Viscous mineral oil composition containing minor proportions of anoil soluble, water in soluble, sufficiently non-volatile alkyl amineester of sulfurous acid active to enhance the lubricating value of saidoil.

2. Viscous mineral oil composition containing minor proportions of anoil soluble. water insoluble, sufficiently non-volatile additive activeto enhance the lubricating value of said oil, said additive comprising ahalogen-free compound conforming to the general formula 1 wherein R isfrom the group consisting of alkyl and substituted alkyl radicals and Xis from the group consisting of O or N(R).

3. Viscous mineral oil composition containing minor proportions of anoil soluble, water insoluble, sufllciently non-volatile halogen-freeadditive active to enhance the lubricating value of said oil, saidadditive comprising a reaction product of thionyl chloride with at leastone member of the class consisting of aliphatic alcohols, substitutedaliphatic alcohols, secondary aliphatic amines, and substitutedsecondary aliphatic amines.

4. Viscous mineral oil composition containing dibutyl sulfite.

ROLSTON L. BOND.

